Answer:
[tex]a_n=1.2 \cdot 2.5^{n-1}[/tex]
Step-by-step explanation:
The first step is to realize that this is a geometric sequence, where each next term in the sequence is 2.5 times larger than the previous. You can confirm this by the fact that 3=1.2*2.5, 7.5=3*2.5, and 18.75=7.5*2.5. Now, you can write the formula, where n is where the number is in the sequence, and a is the number itself. Since 1.2 is the first term in the sequence and the rate of expansion is 2.5, the formula is:
[tex]a_n=1.2 \cdot 2.5^{n-1}[/tex]
Hope this helps!
